[llvm] [InstCombine] Extend bitmask mul combine to handle independent operands (PR #142503)

[Yingwei Zheng via llvm-commits]

dtcxzyw wrote:

>  Moreover, we still need to do the analysis to check for the conditions of reassociation. Thus, it is somewhat unclear if this change is a net positive.

I don't think it is necessary to check the specific pattern. As these two muls share the same constant factor, it is always profitable to reassociate the tree. `ReassociatePass` performs the reassociate for add, but not for `or disjoint`: https://godbolt.org/z/TMcYTdd5T It may be better to handle this pattern in `ReassociatePass`.



https://github.com/llvm/llvm-project/pull/142503